1. Field of the Invention
This invention relates to naphthalene derivatives which have an allyl or propenyl group or groups and which are effective when used in various curable resin compositions or as a modifier for various types of curable resins. The derivatives are excellent in working properties and heat resistance and are able to provide a cured product having high strength and high glass transition temperature.
2. Description of the Prior Art
Thermosetting resins have been widely used in the electric and structural fields as casting, dipping, laminating and molding materials. In recent years, there is a tendency toward severe conditions of use of the materials in these fields. Especially, importance is placed on the heat resistance and the low water absorptivity of the materials.
Known epoxy polymers which are typical of heat-resistant thermosetting resins include, for example, epoxidized phenol-novolac products (e.g. Epikote commercially available from Yuka-Shell Epoxy Co., Ltd.), epoxidize cresol-novolac products (e.g. EOCN available from Nippon Kayaku Co., Ltd.), methylenedianiline tetraepoxide, epoxidized tri- or tetra(hydroxyphenyl)alkanes and the like. There are also known as phenolic resins phenol-novolac resins, ortho-cresol-novolac resins, bis-phenol A, triphenol methane and the like resins.
Although the cured products obtained from these resins all exhibit relatively high heat resistance, the heat resistance is not always satisfactory, coupled with the disadvantage that in order to develop practical strength, heating at high temperatures over a long term is essentially required. In addition, the working properties are not satisfactory.